Insulating a dormer house
Discussion
DoubleSix said:
Cheers, that makes sense. So having increased the depth of the rafter, how do ensure the kingspan stuff doesn't get pushed back into your void. Is it common to batten the sides of the rafter to prevent this?
OP sorry for hijacking your thread, hopefully im asking q's that will benefit you!
Nails, screws or rafter clipsOP sorry for hijacking your thread, hopefully im asking q's that will benefit you!
http://www.toolstation.com/shop/p44294?mkwid=s2W9e...
I've just done this to a Victorian house I'm renovating.The walls and ceilings in the loft were well past their best anyway so we stripped it back to the rafters.The rafters were only 70mm, so we added 50mm to them, then fitted 80mm Celotex in between the rafters and 40mm to the underside, the flat ceiling was insulted with 250mm of rock wool and the low wall got 100mm Celotex.All to joints on the Celotex were sealed with 75mm wide silver tape, then the walls and ceilings plaster boarded.
-Pete- said:
I also wondered about the space under the floorboards through which the wind whistles thanks to vents in the soffits. Our floors (3) are cold, is there anything I can do to limit the airflow without causing problems?
Our floors are cold too - Last year we upgraded our heating system from a one pipe to a two pipe system, and while the floorboards were up in our main bedroom the breeze coming through the floor was unbelievable. I would also be interested to know the answer to this one - i.e. can I just stuff the ends of each joist in the floor with rockwool? Or will that cause issues?Thanks for the answers on here chaps, it's coming in very useful - Would be good to know if anyone knows of any good deals to be had on this stuff too...
JohnStitch said:
I would also be interested to know the answer to this one - i.e. can I just stuff the ends of each joist in the floor with rockwool? Or will that cause issues?
.
Should be no reason why not. If you wanted to you could insulate 150-200 of Rockwool or loft insulation between all the joists. Makes a noticeable improvement..
Does anyone have any experience of blown in insulation? I've been looking at Cellulose & Mineral wool fibres, Polyurethane Urea & Formaldehyde foams, and Perlite/Vermiculite & Expanded Polystyrene granules. Each have their pro's and cons. Any ideas on cost for a four bed detached house?
Thread resurrection - Got all the work booked in for September, so am now trying to source all the materials.
Does anyone know if Xtratherm is any good in comparison to Celotex? Seems to be quite significantly cheaper, just wondered if that was just because it's not such a well known brand, or if it is an inferior product in comparison.
And does anyone know where I can get a good price on 100mm rockwool type insulation? I remember seeing this stuff on offer at 3 quid a roll a year or two ago, now it's around £30. Gonna need quite a few rolls...
Does anyone know if Xtratherm is any good in comparison to Celotex? Seems to be quite significantly cheaper, just wondered if that was just because it's not such a well known brand, or if it is an inferior product in comparison.
And does anyone know where I can get a good price on 100mm rockwool type insulation? I remember seeing this stuff on offer at 3 quid a roll a year or two ago, now it's around £30. Gonna need quite a few rolls...
Not sure if anyone's interested, but the renovations started today and as suspected there was literally no insulation in the older part of the house....apart from this little bit lol
I'm sure that thin stripe made the world of difference. I have a feeling our house was the last to be built on this street, so maybe the builders ran out of insulation and just couldn't be bothered to get more. Every other house owner on this street says how hot their upstairs is. Ours is bloody freezing, and this is why!
More pics here...
The newer part of the house has more insulation in it, but not brilliant, this is all being ripped out and replaced with Celotex + rockwool in the eaves
So next stop, is all the floors up and replaced, insulate everywhere and reboard, next week plastering, following week all new woodwork fitted, then decorated and carpeted, then back to normal hopefully, and a winter of a warm upstairs with gas bills that are less than £45-50 per week, fingers crossed.
I'm sure that thin stripe made the world of difference. I have a feeling our house was the last to be built on this street, so maybe the builders ran out of insulation and just couldn't be bothered to get more. Every other house owner on this street says how hot their upstairs is. Ours is bloody freezing, and this is why!
More pics here...
The newer part of the house has more insulation in it, but not brilliant, this is all being ripped out and replaced with Celotex + rockwool in the eaves
So next stop, is all the floors up and replaced, insulate everywhere and reboard, next week plastering, following week all new woodwork fitted, then decorated and carpeted, then back to normal hopefully, and a winter of a warm upstairs with gas bills that are less than £45-50 per week, fingers crossed.
Also really interested to see how this progresses.
I have a similar refurb (which will start, eventually, once I've solved the structural problems), but I've got the added complication of needing to add wind bracing while I'm in there...
To avoid a huge cold bridge at the head of wall (4) on your diagram, are you going to remove that wall and insulate the rafters all the way down to the eaves? Rather than just insulating wall (4) itself and the ground floor ceiling behind - that's what I'm thinking of doing, anyway (plus none of those walls are particularly vertical in my house...)
Some of that insulation looks rather mouldy. Don't forget either a vapour barrier immediately behind the plasterboard or to install the celotex foil side facing inwards and then tape all the joints with the special tape.
I have a similar refurb (which will start, eventually, once I've solved the structural problems), but I've got the added complication of needing to add wind bracing while I'm in there...
To avoid a huge cold bridge at the head of wall (4) on your diagram, are you going to remove that wall and insulate the rafters all the way down to the eaves? Rather than just insulating wall (4) itself and the ground floor ceiling behind - that's what I'm thinking of doing, anyway (plus none of those walls are particularly vertical in my house...)
Some of that insulation looks rather mouldy. Don't forget either a vapour barrier immediately behind the plasterboard or to install the celotex foil side facing inwards and then tape all the joints with the special tape.
JohnStitch said:
...pics...
You need to seal under where your floor starts under where the vertical stud walls rest, between the timber and the ceiling below. That'll stop any draught under the dormer floor. Kingspan offcuts and foam.For the sake of a few inches of roomspace if possible I'd go right across the front of the rafters and vertical timbers with a full sheet of 3-4" insulation - gives good ventilated space behind it for the wood to breathe, and insulates much better than infilling between timbers. Easier and quicker than cutting board into bits - it's a horrible job cutting rigid foam board - and then having to foam the gaps where you cut the boards too small. Theres clever non-metal screws available now that don't conduct heat.
Foam and then 2" ally tape over all the board joints, and completely cover that section of solid timber below the newer window in 4th pic with tape to seal it. Foam gun around all windows/french doors against the timbers before anything else.
Air tightness is the key to the insulation I reckon - but I'm not a builder, just a diyer.
Kingspan/celotex/xtratherm etc all do equivalent boards - there might be a small difference but price is the key.
Seconds and Co or A&A Insulation do seconds quality boards which are perfectly usable and cheap.
Worth a rewire while it's all accessible? Re position lights, Cat 5, extra sockets etc?
Yep, all being done Andy. Electrician is here now, scratching his head as there's some very strange electrics going on. What started as a load of extra sockets is ending up as pretty much a whole rewire. CAT6 is routed up to the loft ready to drop down into each room too. Was hoping I'd find some goodies under the floor, so far we have a man utd magazine from 1986, an Enid blyton magazine from 1953, and a letter to a previous owner from 1968. No jewellery yet 
Day 2....Floors are all up and the insulation is starting to go in, filling up the floors of the eaves to the joins with the vertical walls, then celotexing the rest
The state of this dormer is shocking. You can see the outside all around the cheeks as the lead flashing leaves a lot to be desired. This will be sorted out in the Spring when we get the chimney repointed and have scaffold up. Meanwhile lots of clear silicone and expanding foam is our friend. Not really the right way to do it, but will do in the short term. It's a very steep pitched roof and so far have had no water ingress (fingers crossed), so hopefully if we block it up it'll last until we have the scaffold. The amount of wasps nests I have found is ridiculous - thankfully they have all been dead...
First fix electrics also gone in today, with pretty much a rewire - lots of alterations seem to have been made in the past by previous owners leaving us with 2 ring mains upstairs, 2 downstairs, and lots of other strange business inbetween. Also the all important CAT6 cables are now fed to each room (2 to each), along with Coax aeriel cable.
Tomorrow, more of the same, getting everything insulated, reinstating the flooring, then plasterboarding to be ready for plasterers next week...
The state of this dormer is shocking. You can see the outside all around the cheeks as the lead flashing leaves a lot to be desired. This will be sorted out in the Spring when we get the chimney repointed and have scaffold up. Meanwhile lots of clear silicone and expanding foam is our friend. Not really the right way to do it, but will do in the short term. It's a very steep pitched roof and so far have had no water ingress (fingers crossed), so hopefully if we block it up it'll last until we have the scaffold. The amount of wasps nests I have found is ridiculous - thankfully they have all been dead...
First fix electrics also gone in today, with pretty much a rewire - lots of alterations seem to have been made in the past by previous owners leaving us with 2 ring mains upstairs, 2 downstairs, and lots of other strange business inbetween. Also the all important CAT6 cables are now fed to each room (2 to each), along with Coax aeriel cable.
Tomorrow, more of the same, getting everything insulated, reinstating the flooring, then plasterboarding to be ready for plasterers next week...
DoubleSix said:
As it’s been resurrected... what happened after Day 2 John??
Since then we’ve pretty much refurbed the entire house, added an extension, and now finishing off the garden - for a house that I thought only needed a lick of paint, it’s been quite expensive! Worth it though - I did take photos of the entire process so can upload some of them here if people want to see them....Joyrider1 said:
Since then we’ve pretty much refurbed the entire house, added an extension, and now finishing off the garden - for a house that I thought only needed a lick of paint, it’s been quite expensive! Worth it though - I did take photos of the entire process so can upload some of them here if people want to see them....
Yes please!Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff